7,058 research outputs found
Three-body effects in the Hoyle-state decay
We use a sequential -matrix model to describe the breakup of the Hoyle
state into three particles via the ground state of . It
is shown that even in a sequential picture, features resembling a direct
breakup branch appear in the phase-space distribution of the
particles. We construct a toy model to describe the Coulomb interaction in the
three-body final state and its effects on the decay spectrum are investigated.
The framework is also used to predict the phase-space distribution of the
particles emitted in a direct breakup of the Hoyle state and the
possibility of interference between a direct and sequential branch is
discussed. Our numerical results are compared to the current upper limit on the
direct decay branch determined in recent experiments
Study of Beam Losses at Injection in the CERN Proton Synchrotron
The maximum intensity the CERN PS has to deliver is continuously increasing. In particular, during the next years, one of the most intense beams ever produced in the PS, with up to 3000 1010 proton per pulse, should be delivered on a regular basis for the CNGS physics program. It is now known that the existing radiation shielding of the PS in some places is too weak and constitutes a major limitation due to large beam losses in specific locations of the machine. This is the case for the injection region: losses appear on the injection septum when the beam is injected in the ring and during the first turn, due to an optical mismatch between the injection line and the PS. This paper presents the experimental studies and the simulations which have been made to understand the loss pattern in the injection region. Possible solutions to reduce the beam losses will be described, including the computation of a new injection optics
Some patterns and social impacts of external migration on a below-replacement population: Denmark by the turn of the millennium
As with many other nations in Europe, Denmark has experienced below-replacement fertility over the past three decades. The impact on population growth of the recent fertility decline to a large extent has been offset by a positive net balance of external migration. To provide a factual basis for a wide range of policy issues and social and cultural impacts we start by studying external migration, differential fertility, naturalization of foreign nationals, and population growth in the framework of multidimensional life models. Migrants and naturalized citizens tend to have reproductive behavior and sex/age profiles that differ significantly from those of the remaining population. To study some concerted demographic and social impacts of such differentials, we construct a number of midterm projections based on existing and expected development of fertility, mortality, and migration
Aprotinin concentrations effective for the inihibition of tissue kallikrein and plasma kallikrein in vitro and in vivo
On the nonextensive character of some magnetic systems
During the past few years, nonextensive statistics has been successfully
applied to explain many different kinds of systems. Through these studies some
interpretations of the entropic parameter q, which has major role in this
statistics, in terms of physical quantities have been obtained. The aim of the
present work is to yield an overview of the applications of nonextensive
statistics to complex problems such as inhomogeneous magnetic systems.Comment: to appear in the Proceedings of the conference CTNEXT07, Complexity,
Metastability and Nonextensivity, Catania, Italy, 1-5 July 2007, Eds. S. Abe,
H.J. Herrmann, P. Quarati, A. Rapisarda and C. Tsallis (American Institute of
Physics, 2007) in pres
Experimental study of the reaction at MeV
Our understanding of the low-lying resonance structure in C remains
incomplete. We have used the reaction at
proton energies of MeV as a selective probe of the excitation
region above the threshold in C. Transitions to individual
levels in C were identified by measuring the 3 final state with
a compact array of charged-particle detectors. Previously identified
transitions to narrow levels were confirmed and new transitions to broader
levels were observed for the first time. Here, we report cross sections, deduce
partial -decay widths and discuss the relative importance of direct and
resonant capture mechanisms.Comment: 9 pages, 7 figures, 5 tables; added details on data analysi
The chemical composition of red giants in 47 Tucanae I: Fundamental parameters and chemical abundance patterns
Context: The study of chemical abundance patterns in globular clusters is of
key importance to constrain the different candidates for intra-cluster
pollution of light elements. Aims: We aim at deriving accurate abundances for a
large range of elements in the globular cluster 47 Tucanae (NGC 104) to add new
constraints to the pollution scenarios for this particular cluster, expanding
the range of previously derived element abundances. Methods: Using tailored 1D
LTE atmospheric models together with a combination of equivalent width
measurements, LTE, and NLTE synthesis we derive stellar parameters and element
abundances from high-resolution, high signal-to-noise spectra of 13 red giant
stars near the tip of the RGB. Results: We derive abundances of a total 27
elements (O, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr,
Mo, Ru, Ba, La, Ce, Pr, Nd, Eu, Dy). Departures from LTE were taken into
account for Na, Al and Ba. We find a mean [Fe/H] = and
in good agreement with previous studies. The
remaining elements show good agreement with the literature, but the inclusion
of NLTE for Al has a significant impact on the behaviour of this key element.
Conclusions: We confirm the presence of an Na-O anti-correlation in 47 Tucanae
found by several other works. Our NLTE analysis of Al shifts the [Al/Fe] to
lower values, indicating that this may be overestimated in earlier works. No
evidence for an intrinsic variation is found in any of the remaining elements.Comment: 22 pages, 16 figures. Accepted for publication in A&
Cost comparison of treating chronic hepatitis C genotype one with pegylated interferons in Ukraine
Reduced Dicer expression in the cord blood of infants admitted with severe respiratory syncytial virus disease
<p>Abstract</p> <p>Background</p> <p>Respiratory syncytial virus (RSV) is one of the most important causes of pediatric hospital admissions in the developed world. The ribonuclease Dicer is an important regulator of gene expression and cellular function via RNA interference, and may also have anti-viral functions. A previous microarray analysis of the cord blood of 5 patients with RSV disease suggested downregulation of <it>Dicer</it>. In order to further investigate whether reduced <it>Dicer </it>expression can predispose newborns to RSV disease, we have analyzed the gene expression of <it>Dicer </it>in the cord blood of 37 infants with confirmed RSV disease.</p> <p>Methods</p> <p>The cord blood of 2108 newborns was collected. 51 had a positive nasopharyngeal aspirate for RSV <1 year, and were grouped according to disease severity. 37 had sufficient cord blood RNA of good quality. <it>Dicer </it>gene expression was assessed by qPCR analysis of cord blood using a TaqMan low-density array and compared to control infants who did not present with RSV disease using the Mann-Whitney test.</p> <p>Results</p> <p>There was significant downregulation of <it>Dicer </it>in the severe disease group: relative quantity 0.69 (95% CI: 0.56 - 0.87), p = 0.002. There was no significant downregulation in the mild disease group.</p> <p>Conclusions</p> <p>We demonstrate reduced <it>Dicer </it>expression in the cord blood of infants with severe RSV disease, prior to RSV exposure. We theorize that this may predispose to RSV disease by disruption of leukocyte gene regulation or direct anti-viral RNA interference mechanisms.</p
Optimal box-covering algorithm for fractal dimension of complex networks
The self-similarity of complex networks is typically investigated through
computational algorithms the primary task of which is to cover the structure
with a minimal number of boxes. Here we introduce a box-covering algorithm that
not only outperforms previous ones, but also finds optimal solutions. For the
two benchmark cases tested, namely, the E. Coli and the WWW networks, our
results show that the improvement can be rather substantial, reaching up to 15%
in the case of the WWW network.Comment: 5 pages, 6 figure
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